Ok I found this when out questing on my mage. In Serpent Lake in Zangarmarsh (Just to the east of Orebor Harborage) you will find alot of these mobs: Mudfin Frenzy - NPCs - World of Warcraft
They have around 1300-1400 health as said on WoWHead and come in packs of atleast 3. On my mage I could round up like 10-20 of them at a time with ice barrier on and just frost nova + cone of cold and then one or two arcane explosion and they were dead.
They drop nice vendor trash that sells for around 1.8g a stack, and each mob drops atleast one vendor trash item. They also have a 25% chance to drop Unidentified Plant Parts - Items - World of Warcraft, so they are great for grinding CE rep before you are honored.
I might aswell add in that I was getting around 200-250 xp for each kill rested, so between 2-4k xp each pull whereas I get 1.1k rested from normal mobs that take just as long to kill.
Hope it helped! :wave: (And sorry if this has been posted before)